1. Field
The present invention relates to a circuit board, a method for manufacturing the same, and a solar cell module. The present invention also relates to a metal foil pattern that is patterned into any shapes by cutting with a blade portion of a metal mold, and a method for punching a metal foil for manufacturing the metal foil pattern. In addition, the present invention relates to a metal foil pattern laminate in which a metal foil pattern that is patterned in any shape by cutting with a blade portion of a metal mold is provided on a base material, and a method of punching a metal foil to manufacture the metal foil pattern laminate.
2. Description of the Related Art
When forming a conductive pattern such as circuit, wiring or the like on a substrate, a conductive pattern is mostly formed by forming a metal thin film on a substrate, and then removing an unnecessary portion of the metal thin film by photo-etching and the like.
Since such a manufacturing method requires many steps, in recent years, sometimes a conductive pattern is formed by adhering a metal foil sheet on a substrate, and then punching the metal foil with a punching blade.
For example, the Patent Document 1 (Japanese Unexamined Patent Application, First Publication No. 2007-76288) describes a method for forming a conductive pattern as an RFID antenna by layering a metal foil sheet, which has a metal foil and an adhesive layer, and a base material; performing punching and temporal fixation of the metal foil sheet with a heated punching blade; and removing an unnecessary portion with an aspirating machine or the like.
Corrosion processes by etching have been utilized to form metal foil patterns of any shape from large area metal foils. In this procedure, an etching-resistant resist material and the like is patterned on a metal foil, and then a portion of the metal foil not having a resist material can be removed by immersing the patterned metal in an etchant and the like. In this procedure, however, patterning of a resist material becomes difficult as an area of a metal foil becomes large. In addition, because a large volume of etchant is used to corrode a metal foil, a large amount of money is required to prepare corresponding equipment, to implement measures for protection of the environment, and the like.
As another patterning method for a metal foil to solve the problem, for example, the Patent Document 2 (Japanese Patent No. 3116209) describes a punching process by using a blade portion of a metal mold. Durability, shape accuracy, and processing area are varied depending on the kind of metal molds; however in recent years, fine patterns such as those of a few hundred micrometers can be formed since the precision of metal molds have increased and metal molds have been able to fit in a large processing area.
When punching a metal foil by the metal mold described above, the durability of the metal mold is a matter of concern. In particular, when punching a metal foil using a blade portion whose tip is formed to have an acute angle, the blade portion tends to be deteriorated. Then, a half-cut process is usually performed to increase the durability of the metal mold. In this process, a metal foil and a cushioning material are punched at the same time, and a tip of a blade portion is pressed from the metal foil-side, and then stopped on a middle portion in the thickness direction of the cushioning material. Accordingly, a tip of the blade portion can be prevented from becoming dull. In addition, by using an adhesive film as a cushioning material, misalignment of the metal foil can be prevented, and thereby a pattern with high-precision can be formed.
Note that although the adhesive film is necessary for the half-cut process to prevent misalignment, it is usually disposed after each time a metal foil is punched.